ExtinctMammals
Extinct Marine Mammals
Condtitions that alter marine mammal environment can stress and bottleneck species
Past Extinctions
- Miocene Whale
- 5.3 million years ago extinct
- Basilosaurus (Gingerich)
- Thought to be reptile, yet was discovered to be a prehistoric whale
- very large and primitive blue whale ancestor
- Caribbean Monk Seal (King)
- closely related to Hawaiian and Mediterranean Monk Seals
- overhunting for oil, overfished food source
- Extinct about 1986 (King
Causes
- Coral Bleaching
- Increase in ocean temperatures
- increased water turbidity
- overfishing/overexploitation
- predatory inflation
Effects
On Humans
• Overexploitation seems to be the main issue – loss of fish from overfishing and poor practices can destroy ways of life, jobs, industries, etc. (Read)
• Marine mammals are often caught as bycatch
• Unregulated harvest
• new and innovative solutions to this problem are required to take account of the socioeconomic conditions experienced by fishermen” (Read)
• Issue of regulation versus deregulation – looking at pros and cons of regulation seeing as it costs a lot, but is significant in saving a species (Read)
o Regulation = politically unpopular (Read)
• Poverty and the collapse of other industries can lead to abrupt changes in local fishing conditions – may start to prey on marine mammals once their value as food and bait is noticed (Read)
o Unregulated and usually unsustainable (Read)
o Peruvian dolphins; anchovy fisheries collapsed so people started hunting dolphins; led to depletion in population (Read)
On Ecosystems
• World’s fisheries are not only impacting marine mammals, but the trophic structure as well – by capturing huge amounts of fish they are causing changes in energy pathways and species numbers (Merritt)
o Affect marine mammals adversely
• Loss of biodiversity/ decline in mammals can cause population imbalances in other species (Munday)
Connection to Coral Reefs
• Lots of extinctions/endangerment is caused by loss of habitats – coral reefs have declined 40 percent world wide (Zimmer)
o Partly a result of global warming (Zimmer)
• Loss of coral due to bleaching/global warming have changed the structure of coral reef ecosystems and communities – lead to changes in the fish communities, which lead to more changes through the trophic levels (Munday)
• Direct relationship between abundance of coral and abundance of coral dwelling fish (Munday)
Prevention
• Oceans, unlike terrestrial ecosystems, are still mostly intact – could easily bounce back if they’re taken proper care of (Zimmer)
o Somewhat uncertain about this though – it’s much harder to track the health of ocean mammals than it is of terrestrial ones (Zimmer)
• Not irreversible yet (Zimmer)
• Regulations for overharvesting of fish – mammals such as dolphins often become entangled in nets and will be benefited by such regulation (Zimmer)
• Still time for humans to stop the damage with effect programs that “limit the exploitation of the oceans” (Zimmer).
• Slowing extinction = cutting back on carbon emissions (Zimmer)
References
King, J. (1956). "The monk seals (genus Monachus)". Bull. Brit. Mus. (Nat. Hist) Zool. 3: 201–256.
Gingerich, Phillip D. 2007. Basilosaurus Cetoides. Encyclopedia of Alabama. Available from: [1]
Les Kauffman and Kenneth Mallory (eds).1984. Grew out of a public lecture series entitled 'Extinction: saving the sinking ark,' held in Boston, Massachusetts, at the New England Aquarium during the fall of 1984.
Read AJ. 2008. The Looming Crisis: Interactions between Marine Mammals and Fisheries Journal of Mammalogy. Journal of Mammalogy 89:541–548.
Munday PL. 2004. Habitat loss, resource specialization, and extinction on coral reefs Global Change Biology. Global Change Biology 10:1642–1647.
Zimmer C. 2015. Ocean Life Faces Mass Extinction, Broad Study Says the New York Times [Internet]. the New York Times [Internet]. Available from: http://www.nytimes.com/2015/01/16/science/earth/study-raises-alarm-for-health-of-ocean-life.html?_r=0